This Standard specifies the signalling protocol for the support
of Recall supplementary service (SS-RE) at the Q reference point
between Private Integrated services Network eXchanges (PINXs)
connected together within Private Integrated Services Network
(PISN).

SS-RE is a supplementary service which provides for the re-direction
of a transferred call back to the served user if the call is unanswered.
SS-RE is only applicable after transfer by join, not after transfer
by rerouteing.

Service specifications are produced in three stages and according
to the method specified in ETS 300 387. This Standard contains
the stage 3 specification for the Q reference point and satisfies
the requirements identified by the stage 1 and stage 2 specifications
in ECMA-213.

The signalling protocol for SS-RE operates on top of the signalling
protocol for basic circuit switched call control, as specified
in ECMA-143, and uses certain aspects
of the generic procedures for the control of supplementary services
specified in ECMA-165.

This Standard also specifies additional signalling protocol requirements
for the support of interactions at the Q reference point between
SS-RE and other supplementary services and ANFs. However, the
interaction with the Call Transfer supplementary service is specified
as part of SS-RE signalling procedures as it is the essential
aspect of the Recall supplementary service.

NOTE
Additional interactions that have no impact on the signalling
protocol at the Q reference point can be found in the relevant
stage 1 specifications.

This Standard is applicable to PINXs which can be interconnected
to form a PISN.

The protocol defined in this Standard forms part of the PSS1
protocol (informally known as QSIG).